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MCAT Physics Question — Lowest Specific Gravity

Which liquid has the lowest specific gravity?


Liquid Mass (grams) Volume (liters)
Sulfuric Acid 920 0.5
Benzene 876.5 1
Propanol 1205 1.5
Water 2000 2


A) Sulfuric Acid
B) Benzene
C) Propanol
D) Water




This question is testing you ability to calculate the specific gravity of a substance given the mass and volume. To answer this question, you must know that specific gravity is equal to the density of the substance divided by the density of water. Therefore, the liquid with the lowest specific gravity will have the lowest density.


To solve for density, you must take the mass and divide it by the volume.


ρsulfuric acid = mass/volume = (920 g)/(0.5 L) =1840 g/L

ρbenzene = mass/volume = (876.5 g)/(1 L) = 876.5 g/L

ρpropanol = mass/volume = (1205 g)/(1.5 L) = 803.33 g/L

ρwater = mass/volume = (2000 g)/(2 L) = 1000 g/L


The liquid with the lowest density and thus the lowest specific gravity is propanol making C the correct answer.


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